Variability in particle attenuation and chlorophyll fluorescence in the tropical Pacific: Scales, patterns, and biogeochemical implications - Laboratoire Microorganismes : Génome et Environnement Accéder directement au contenu
Article Dans Une Revue Journal of Geophysical Research. Oceans Année : 1999

Variability in particle attenuation and chlorophyll fluorescence in the tropical Pacific: Scales, patterns, and biogeochemical implications

M Babin
C Cailliau
  • Fonction : Auteur
Jc Marty
  • Fonction : Auteur
  • PersonId : 861906
  • IdRef : 153584017
D Tailliez
  • Fonction : Auteur
D Vaulot

Résumé

The variability in particle attenuation (c(p)) and in chlorophyll in situ fluorescence (F-is) was examined in November 1994 along 150 degrees W in the Pacific Ocean. Two main sources of variation in c(p) and F-is profiles are identified by analyzing data from a 16 degrees S-1 degrees N transect, and from two 5 day stations (5 degrees S and 16 degrees S). The first source reflects changes in the trophic status resulting from prevailing hydrodynamical regimes at large scales. By using flow cytometric data and some assumptions about the size distribution of the different biological stocks, a decomposition of c(p) into its vegetal (c(veg)) and nonvegetal (c(nveg)) components is attempted. Within the euphotic layer, c(veg) accounts for 43% of the total c(p) Signal at the equator and for only 20% in the South Pacific gyre. The nonvegetal component is then subdivided into heterotrophic organisms and detritus contributions. The detrital material is an important contributor with 43% of c(p) at 5 degrees S and 55% at 16 degrees S. A further decomposition of F-is and c(veg) into the three dominant phytoplanktonic groups (Prochlorococcus, Synechococcus, and picoeucaryotes) confirms that picoeucaryotes are important contributors of the vegetal biomass, especially within and below the deep chlorophyll maximum (DCM) (>50% of the algal stock) at 16 degrees S. The second, and essentially local, source of variation is related to specific rhythms in biological and physiological processes. The prominent signals detected during the time series occur at the daily scale: besides the pronounced fluorescence depression at noon in upper layers, particle attenuation in all the layers examined and fluorescence in the DCM display conspicuous daily oscillations. They result from the balance between daytime accumulation and night removal of particles, of algal cells in particular. Finally, the estimation of cp-based growth rates points out the surprisingly rapid turnover time of the whole particulate matter stock in oligotrophic waters (16 degrees S), not only in the euphotic zone (0.63 d(-1)) but also within the dimly lit layers of the DCM (0.36 d(-1)). The corresponding growth rate at 5 degrees S, within a quasi-mesotrophic regime, is 0.47 d(-1) within the euphotic zone.

Domaines

Océanographie
Fichier principal
Vignette du fichier
ark _67375_WNG-3VB2B9G0-3.pdf (2.39 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-03284914 , version 1 (14-07-2021)

Licence

Copyright (Tous droits réservés)

Identifiants

Citer

Hervé Claustre, A Morel, M Babin, C Cailliau, D Marie, et al.. Variability in particle attenuation and chlorophyll fluorescence in the tropical Pacific: Scales, patterns, and biogeochemical implications. Journal of Geophysical Research. Oceans, 1999, 104 (C2), pp.3401-3422. ⟨10.1029/98JC01334⟩. ⟨hal-03284914⟩
82 Consultations
45 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More